From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755430AbaEMGGn (ORCPT ); Tue, 13 May 2014 02:06:43 -0400 Received: from mail-qg0-f41.google.com ([209.85.192.41]:36830 "EHLO mail-qg0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754515AbaEMGGm (ORCPT ); Tue, 13 May 2014 02:06:42 -0400 MIME-Version: 1.0 Reply-To: mtk.manpages@gmail.com In-Reply-To: <1399944913.2648.56.camel@buesod1.americas.hpqcorp.net> References: <1398090397-2397-1-git-send-email-manfred@colorfullife.com> <1399406800.13799.20.camel@buesod1.americas.hpqcorp.net> <1399414081.30629.2.camel@buesod1.americas.hpqcorp.net> <5369C43D.1000206@gmail.com> <1399486965.4567.9.camel@buesod1.americas.hpqcorp.net> <1399490251.4567.24.camel@buesod1.americas.hpqcorp.net> <1399841186.8629.6.camel@buesod1.americas.hpqcorp.net> <1399944913.2648.56.camel@buesod1.americas.hpqcorp.net> From: "Michael Kerrisk (man-pages)" Date: Tue, 13 May 2014 08:06:21 +0200 Message-ID: Subject: Re: [PATCH v2] ipc,shm: document new limits in the uapi header To: Davidlohr Bueso Cc: Manfred Spraul , Davidlohr Bueso , Martin Schwidefsky , LKML , Andrew Morton , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Greg Thelen , aswin@hp.com, "linux-mm@kvack.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 13, 2014 at 3:35 AM, Davidlohr Bueso wrote: > On Mon, 2014-05-12 at 09:44 +0200, Michael Kerrisk (man-pages) wrote: [...] >> The problem is that part of your text is still broken grammatically In >> particular, the piece "Both SHMMAX and SHMALL have their default >> values to the maximum limit" at the very least lacks a word. That's >> what prompted me to propose the alternative, rather than just say >> "this is wrong"--and I thought that I might as well make a more >> thoroughgoing attempt at helping improve the text. >> >> I agree that text something like this should land in the man page at >> some point, but as long as we're going to the trouble to improve the >> comments in the code, let's make them as good and helpful as we can. > > Fair enough, and I trust your grammar corrections over mine ;) Thanks > for taking a closer look. I've added your text below. Thanks. Acked-by: Michael Kerrisk Cheers,' Michael > 8<------------------------------------------ > From: Davidlohr Bueso > Subject: [PATCH v3] ipc,shm: document new limits in the uapi header > > This is useful in the future and allows users to > better understand the reasoning behind the changes. > > Signed-off-by: Davidlohr Bueso > --- > include/uapi/linux/shm.h | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h > index 74e786d..1fbf24e 100644 > --- a/include/uapi/linux/shm.h > +++ b/include/uapi/linux/shm.h > @@ -8,17 +8,20 @@ > #endif > > /* > - * SHMMAX, SHMMNI and SHMALL are upper limits are defaults which can > - * be modified by sysctl. > + * SHMMNI, SHMMAX and SHMALL are default upper limits which can be > + * modified by sysctl. The SHMMAX and SHMALL values have been chosen to > + * be as large possible without facilitating scenarios where userspace > + * causes overflows when adjusting the limits via operations of the form > + * "retrieve current limit; add X; update limit". It is therefore not > + * advised to make SHMMAX and SHMALL any larger. These limits are > + * suitable for both 32 and 64-bit systems. > */ > - > #define SHMMIN 1 /* min shared seg size (bytes) */ > #define SHMMNI 4096 /* max num of segs system wide */ > -#define SHMMAX (ULONG_MAX - (1L<<24)) /* max shared seg size (bytes) */ > -#define SHMALL (ULONG_MAX - (1L<<24)) /* max shm system wide (pages) */ > +#define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */ > +#define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */ > #define SHMSEG SHMMNI /* max shared segs per process */ > > - > /* Obsolete, used only for backwards compatibility and libc5 compiles */ > struct shmid_ds { > struct ipc_perm shm_perm; /* operation perms */ > -- > 1.8.1.4 > > > > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/